Although people infected with Helicobacter pylori have an increased risk of stomach cancer, only some develop the malignancy. Now, new findings by researchers at the University of Porto, in Portugal, and colleagues indicate that stomach cancer risk can be substantially increased when people with specific gene variants, or polymorphisms, are infected with certain strains of H pylori (J Natl Cancer Inst. 2002;94:1680-1687).

In the study of 221 people with chronic gastritis and 222 people with stomach cancer, the investigators analyzed H pylori DNA (from patient specimens) for genetic variations in two virulence-associated genes. They also analyzed each patient's DNA for genetic variations in two genes: the gene that encodes interleukin 1β, and the gene for interleukin 1 receptor antagonist. Certain versions of these genes can lead to severe and chronic gastric inflammation, decreased acid secretion, and gastric atrophy, ultimately resulting in development of stomach cancer.